I'm arguing that flexibility has a cost, and unless you can show me a tangible benefit, it's unnecessary cost. That you can build an OO system comparable to what other languages have built-in is a compelling demonstration of the extent of the flexibility, but it isn't a compelling demonstration of the need for the flexibility. Surely you have better examples of the extensibility of the language than stealing well-understood ideas from other languages. The best time to bring those out would be when wooing new users. In other words, your Prolog-style unification engine, your LINQ, your dependent-typing system, etc. would be better demonstrations of the vitality and power of your language's flexibility and extensibility than things I get for free by typing "python" at my shell prompt.
DBIx::Class. I don't want to go to the effort of going into massive detail here, but in short: It allows you to write SQL access code under which you can use ANY database (SQLite, MySQL, MSSQL, Postgres, what have you), without changing a single line of your code. It will not only deploy your schema onto the database server, but also optimize your queries, so that for anything of slight complexity, it will likely be faster than your hand-written queries.
>>That you can build an OO system comparable to what other languages have built-in
My explicit point was that it is better [edit: which was an answer to your question about value from flexibility, compared to the cognitive cost], don't do straw man attacks please. (Are you trolling?)
Edit: Thanks for the downvote. :-)
Edit 2: As answer to the next long, long comment with parts going all over: Of course complexity has costs. if you really just want a good reference on Moose to see exactly what it is, ask Mithaldu. He probably has better sources than me. This is what I give people (it is getting old): http://rjbs.manxome.org/talks/moose/Moose.pdf
Edit 3: And to avoid being called a "troll" -- don't write shit like "In 2013 nearly every problem has a language more appropriate than Perl." while you acknowledge you don't know the subject...
Actually, the Moose PDF is still the one i link to when necessary. However lately i've switched to simply linking to http://perl-tutorial.org and pointing out the relevant bits.
When someone says two systems are comparable, it is a different claim than that two systems are equivalent. In order for something to be better than something else they have to be comparable. Dynamic typing can be better than static typing only because they're both approaches to typing (please don't confuse this example with an opinion); static typing cannot be better than lexical scope because they're not comparable.
We're talking about the cost/benefit of flexibility as evidenced by systems like Moose. It's quite irrelevant to my point whether Moose is better or not, so it is quite a stretch to accuse me of a straw man attack. For that to be the case, I'd have to have said that Moose is worse than (say) Python's OO therefore flexibility is bad and Perl is bad by extension. What I'm actually saying is that flexibility isn't free, it has a cost, and that the cost must be offset by other benefits. If Moose is better, that's a benefit that might outweigh the cost, but nobody seems to be interested in telling me how it's better when they could instead attack the argument, by, for instance, hauling out the well-worn stack of logical fallacy accusations. If I sound irritable, it's only because I start conversations on HN in good faith expecting, you know, a conversation, and these kinds of vitriol-powered slamfests are not what I have in mind. Am I a troll indeed.
Edit: One need not know a language to find oneself in a niche where that language might be more appropriate. I didn't mean that remark to offend and I regret my wording. I certainly wasn't out to troll. That said, surely you do not believe one must learn a language inside out before knowing whether it is appropriate to a domain. I know many languages and work in several domains and never find myself thinking Perl would be better. I might not be in the right domains, but if we were having this conversation about C++, Java or Haskell it would be easier to rattle off a few example domains rather than scoff at the question.
>> surely you do not believe one must learn a language inside out before knowing whether it is appropriate to a domain.
You had a hard opinion about something you admitted you don't know. That is just not a serious position.
>>We're talking about the cost/benefit of flexibility
Of course it has a cost with flexibility. The same goes for lisp variants, which have an even larger flexibility than Perl in the macro system. Since you claim to know many other systems than Python, you should know this...?
Every design choice have costs/benefits. You don't need to repeat that trivial point as if it is news.
(That you think another OO system is better without knowing both says more about you than anything else.)
And now you argue that because you (allegedly) know other stuff, your opinion is relevant?
(Why don't you go argue that the flexibility of easily reprogrammable syntax is bad with Lisp people instead? If Perl is bad according to you, their life must be Hell?)
(And fyi, re niches, all the scripting languages are very similar in capabilities and fill mostly the same niche. That is why we see so many language wars trolls from the aggressive language communities. But I think you know this.)
All this discussion is doing is illustrating your rescue-dog mentality. Don't worry, I won't waste another second on Perl. Enjoy your Detroit, you guys have earned it.
Your "classy" insults aren't exactly screaming non-troll.
If you really are a non-troll wanting to seriously discuss a subject's pro/con, don't start with insults and then act innocent. I was polite to the first dozen language war trolls on HN claiming things were shit they have no clue about. That was a long time ago.
(Also, the net is full with Moose info -- I gave you my favorite reference and suggested you'd ask others. If you really wanted to read about roles, typing of attributes etc and build a serious opinion.)
PS For the third time: Have fun explaining to Lisp people your theories about flexibility's cost being too high. I'd love to see your insults to their reaction... DS
